A great travel blog by WSJ journalist Niraj Seth about his travel through the south of India in an auto-rickshaw - On the Road in India
Excerpt about using a horn while driving :-)
"The horn is your friend. Use it often, use it well. Unlike in the US, where a honk usually signals an imminent emergency (or unpardonable rudeness) honking is a way of life in India. Anything can cross your path at any time — people walking down the middle of the highway in the dark, motorcycles traveling the wrong way, a tire rolling across a street — so it’s wise to keep one hand on or near the horn. Drivers here blow the horn when they’re passing pedestrians, presumably to alert them to an approaching vehicle. They honk to rouse the cars placidly drifting into the oncoming lane. Sometimes they even honk on completely empty streets — out of habit, perhaps."